1. Field of the Invention
The present invention relates to circuit apparatus for selectively variably setting remanent magnetic flux density in magnetic cores which are part of magnetic circuits responsive to such setting. This type of circuit apparatus is sometimes referred to as a core drive circuit.
2. Description of the Prior Art
A specific application of circuit apparatus of the type referred to is as a component of ferrite core phase-shifter assemblies employed in phased antenna systems. The advent of phased arrays containing many individual radiators has caused a high degree of interest in reducing the cost of core driver circuits. The design technique for such circuits have included circuits which employ so-called two-cycle operation, and circuits which employ so-called three-cycle operation. In the two-cycle operation the magnetic remanence is reset to its referenced insertion state along the flux density (B) versus magnetizing force (H) hysteresis loop curve (the first cycle) and then set to the desired new setting (the second cycle). In the three-cycle operation the previously set flux density state is passed along the hysteresis loop to a full-set condition (first cycle), then reset to the insertion state (second cycle) and finally set to the new desired setting (third cycle). The three-cycle operation provides more effective erasure of a previous set state than the two cycle operation.
In the prior art, the broad approach of employing a flux circuit regenerative feedback via a feedback winding to achieve circuit switching and self-blocking oscillator relationships is known. An example is disclosed in U.S. Pat. No. 3,159,752 to J. Domberg et al., which discloses this approach in connection with a one-shot pulse generator.
Also known in the prior art is the technique of sensing the magnitude of flux density in a core being driven by a drive circuit by integrating the voltage from a winding other than the drive winding. An example of such circuit is disclosed in U.S. Pat. No. 3,510,675 to T. A. Johnson et al.
Prior to the present invention there has been no known use of regenerative feedback in the sequencing of a drive circuit through the previously referred to cycles, nor the combination of regenerative feedback techniques with the technique of sensing flux density by the integration of a voltage from a second winding.